This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | -231 |
| 3 | -6436 |
| 4 | -64911 |
| 5 | -387500 |
| 6 | -1663991 |
| 7 | -5686676 |
| 8 | -16386591 |
| 9 | -41093596 |
| 10 | -90234375 |
| 11 | -165530756 |
| 12 | -185841071 |
| 13 | 404972404 |
| 14 | 4627726569 |
| 15 | 27954687500 |
| 16 | 148292923329 |
| 17 | 755963695684 |
| 18 | 3803677305049 |
| 19 | 19056502765084 |